The invention relates to a crane, particularly a rubber-wheel container crane comprising a frame which has, on opposite sides of its lower part, main beam structures at both ends of which, i.e. in the lower corners of the crane, there are in each particular case two successive rubber wheels or wheel arrangements through which the crane is supported to its moving carrier.
The crane is thus supported to the carrier by means of wheels in the corners of the above-described structure. When the wheel load exceeds the load capacity limit of the wheel, more than one wheel per corner is required, whereby the corner load is divided between two or more wheels, and to divide the wheel load equally, an articulated balancing scale is typically constructed between them. In addition, in machines of a straddle carrier type, the wheels are suspended, and in some cases active springs have also been used.
This design originates from a crane moving on considerably uneven terrain. When one drives a crane with rubber wheels on relatively even terrain, such as in harbour yards, this structure is unduly complex and expensive, having thus also a great deal to be maintained and a large number of parts that wear. In some cases, maintenance of the scale articulation has been necessary as early as after one year of productive operation. Maintenance may take several days, and the crane may be out of productive operation for more than a week in total.